/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    NoSplit.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.classifiers.trees.j48;

import weka.core.Instance;
import weka.core.Instances;

/**
 * Class implementing a "no-split"-split.
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision$
 */
public final class NoSplit extends ClassifierSplitModel {

    /** for serialization */
    private static final long serialVersionUID = -1292620749331337546L;

    /**
     * Creates "no-split"-split for given distribution.
     */
    public NoSplit(Distribution distribution) {

        m_distribution = new Distribution(distribution);
        m_numSubsets = 1;
    }

    /**
     * Creates a "no-split"-split for a given set of instances.
     *
     * @exception Exception if split can't be built successfully
     */
    public final void buildClassifier(Instances instances) throws Exception {

        m_distribution = new Distribution(instances);
        m_numSubsets = 1;
    }

    /**
     * Always returns 0 because only there is only one subset.
     */
    public final int whichSubset(Instance instance) {

        return 0;
    }

    /**
     * Always returns null because there is only one subset.
     */
    public final double[] weights(Instance instance) {

        return null;
    }

    /**
     * Does nothing because no condition has to be satisfied.
     */
    public final String leftSide(Instances instances) {

        return "";
    }

    /**
     * Does nothing because no condition has to be satisfied.
     */
    public final String rightSide(int index, Instances instances) {

        return "";
    }

    /**
     * Returns a string containing java source code equivalent to the test made at
     * this node. The instance being tested is called "i".
     *
     * @param index index of the nominal value tested
     * @param data  the data containing instance structure info
     * @return a value of type 'String'
     */
    public final String sourceExpression(int index, Instances data) {

        return "true"; // or should this be false??
    }

}
